This invention relates generally to multimedia RGB signal processors and specifically to a multimedia RGB preamplifier capable of processing very high frequency analog signals.
Recent developments in video display systems, such as those used in television receivers and monitors, have included elaborate systems for overlaying one video signal upon another, mixing video signals and in picture-in-picture systems, replacing a portion of a video signal with another video signal or an alphanumeric character display. The range of display variations is vast. In a television studio environment, sophisticated and expensive equipment is required to provide such multimedia visual presentations. Such equipment, even though expensive, is limited in terms of its frequency handling capability since it generally uses digital processing. In the proposed HDTV (high definition television) broadcasting systems, the bandwidth of the video signal will be on the order of 35 to 40 MHz rather than the 4 to 5 MHz used in the present NTSC system. Since digital processing requires converters and the like to operate at a minimum of twice the highest frequency to be processed, there will be a need for other than digital processing to generate multimedia displays.
The present invention includes circuitry for overlaying one video signal (the secondary signal) on another video signal (the primary signal). Both the brightness and contrast of each of the primary and secondary signals are independently adjustable and the mixing ratio of the two signals is variable to allow for the provision of various special effects, such as gradually blending the graphics overlay into and out of the main video image.